/*
 * Copyright 2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package be.free.ts.support;

/**
 * @author Christophe De Blende
 * @since 02/01/13
 */
public class SsinService {

	private static final int SSIN_LENGTH = 11;

	public boolean isValid(String value) {
		if (value == null) {
			return false;
		}

		if (value.length() != SSIN_LENGTH) {
			return false;
		}

		try {
			return isValidMod97(value) || isValidMod97("2" + value);
		} catch (NumberFormatException e) {
			return false;
		}

	}

	private boolean isValidMod97(String value) {
		long niss = Long.valueOf(value);
		long digit = niss / 100;
		long checkDigit = 97 - digit % 97;
		return niss == 100 * digit + checkDigit;
	}
}
